Association between left atrial myocardial function and exercise capacity in patients with either idiopathic or ischemic dilated cardiomyopathy: a two-dimensional speckle strain study.

BACKGROUND: In patients with idiopathic dilated cardiomyopathy (DCM) a more depressed left atrial (LA) booster pump function has been observed compared to ischemic patients although under similar loading conditions, and attributed both to altered LA overload and to LA larger involvement in the myopathic process. AIM OF THE STUDY: To detect by speckle-tracking two-dimensional strain (2DSE) LA systolic dysfunction in patients with either idiopathic or ischemic DCM, and to assess in these patients possible correlation between LA myocardial function and exercise capacity during cardiopulmonary test.
METHODS: Three-hundred-fourteen patients (52.4+/-11.2 years) with either idiopathic (160 patients) or ischemic (154 patients) DCM underwent cardiopulmonary stress test, standard Doppler echo and 2DSE analysis of atrial longitudinal strain in the basal segments of LA septum and LA lateral wall, and in LA roof.
RESULTS: The two groups were comparable for most of clinical variables. LV volumes, ejection fraction, stroke volume, and mitral valve effective regurgitant orifice were similar between the two groups. No significant differences were evidenced in Doppler transmitral inflow measurements. Also LA diameter and maximal volume were similar between the two groups. Conversely, LA active empting volume and fraction were both lower in patients with idiopathic DCM (<0.001). Peak systolic myocardial atrial strain was significantly reduced in patients with idiopathic DCM compared with ischemic DCM at the level of all the analyzed atrial segments (p<0.0001). By multivariable analysis, in the overall population, ischemic aetiology of DCM (p<0.0001) and LA volume (p<0.001) were the only independent determinants of LA lateral wall systolic strain. On the other hand, LA lateral wall systolic strain (p<0.0001) and LA volume (p<0.001) were powerful independent predictors of peak oxygen consumption during cardiopulmonary exercise testing.
CONCLUSIONS: Two-dimensional strain represents a promising non-invasive technique to assess LA atrial myocardial function in patients with DCM. LA systolic deformation is more depressed in idiopathic compared with ischemic DCM, and is closely associated with functional capacity during effort. Future longitudinal studies are warranted to further our understanding of the natural history of LA myocardial function, the extent of reversibility of LA dysfunction with therapy, and the possible prognostic impact of such indexes in patients with congestive heart failure.